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Black-footed ferrets image courtesy of the USFWS.

Pesticides: they’re in our food, our water, and our environment. In a recent biological opinion open for public comment until the end of this week, the U.S. Fish and Wildlife Service says that the use of one in particular, Rozol, could kill black-footed ferrets and aplomado falcons, not to mention other raptors and even passerine birds.

“We have a number of incidents where we found dead birds that died either from primary or secondary effects,” says Nancy Golden, a toxicologist with the USFWS. Rozol, as well as other rodenticides used on the landscape, are quite toxic to birds as well, she says. “I think there is a growing concern, at least among the wildlife community, for anticoagulants and pesticides.”

Used to control pesky prairie dogs in Great Plains and Rocky Mountain states, Rozol is an anticoagulant, meaning it causes uncontrollable bleeding in anything that ingests it. Even though it is meant to destroy targeted animals, those that eat animals exposed to the pesticide, like black-footed ferrets that eat prairie dogs, are also in danger. The anticoagulant builds up in their bodies, sometimes proving fatal. (Rozol is not a known endocrine disruptor, or synthetic chemical that mimics or interferes with normal hormonal function.)

“Ferruginous hawks, golden eagles, bald eagles, owls, magpies, turkey vultures, badgers, swift foxes, coyotes, raccoons, and grain eaters like wild turkeys and red-winged blackbirds have been turning up dead around Rozol treatment sites, and while some carcasses have yet to be tested, lethal concentrations of Rozol are being found in ones that have been. Rozol also directly threatens the grievously endangered black-footed ferret by both direct poisoning and by destroying its obligate food and refuge source,” Ted Williams wrote in an Incite article titled "Doggone."

Hundreds of thousands of pounds of Rozol are distributed across the landscape, says Ron Klataske, director of Audubon of Kansas, poisoning prairie dogs on a massive scale.

The USFWS is working with private landowners to reintroduce black-footed ferrets in Logan County, Kansas. Yet that county alone bought 46 tons of Rozol Prairie Dog Bait in 2008 to eradicate the animals.

“They have allowed far too loose of a reign on the individual or individuals who have allowed Rozol to surge forward and be used in this fashion and it’s really inexcusable,” he says.

A biological opinion issued by the USFWS, which focuses solely on how Rozol’s use could affect endangered species, states that three of the 21 endangered species assessed—black-footed ferrets, aplomado falcons, and gray wolves—could all still be negatively affected. Although certain measures are in place to reduce the amount of harm, there may still be a number of individuals that die from the chemical’s use.

“We’re not saying no to prairie-dog control, we’re saying no to indiscriminate killing,” says Brian Rutledge, executive director of Audubon Wyoming and National Audubon’s vice president for the Rocky Mountain Region.

The solution, for now, may be to submit a comment to the draft biological opinion stating that more should be done to protect wildlife listed under the Endangered Species Act. Then, “what needs to happen for this progress to continue and accelerate and for the black-footed ferret to remain on the planet is for the EPA to ban Rozol and similar biocides for prairie-dog control,” Williams writes in his article. “That doesn’t seem like much of a hardship for ranchers who have a cheap, safe, effective alternative in zinc phosphide. And that doesn’t seem like a big order for an enlightened administration that, with its superb appointments, has repeatedly demonstrated concern for and understanding of wildlife.”

Click here to see the draft biological opinion, and leave a comment by clicking on “Submit a Comment.”

For more reading on black-footed ferrets and other endangered species, check out our article titled "The Least Among Us."